Certain rotary switch assemblies comprise a plurality of stators and associated rotors, wherein dielectric housing members comprising the stators are stacked together between end housing members and fastened together such as by bolts with nuts or rivets on their ends, with a central rotatable shaft extending through the assembly to rotate the rotors. Such a rotary switch is more particularly disclosed in U.S. Pat. No. 4,497,984 and is sold by AMP Incorporated under AMP Part No. 3-436209-4 for aircraft navigational systems. Each stator has a plurality of electrical terminals having outer contact sections extending outwardly from the assembly for electrical engagement with another article such as a printed circuit board, and the terminals have brush contact portions extending into a shallow cavity formed between adjacent pairs of housing members. A planar rotor member comprising a printed circuit board associated with the stator is disposed in the cavity thereof spaced from both adjacent housing members by bushings about a central opening through which the central shaft extends. The central shaft is profiled in cross-section and the central opening of each rotor is correspondingly profiled for the rotor to be rotated to a selected position thereby for coded electrical engagement between its circuit paths and free ends of spring arms of the brush contact portions of the associated stator. The central shaft is an assembly of an inner shaft independently rotatable within an outer shaft, each with a separate actuator or knob on the respective end thereof forwardly of the panel to which the switch is mounted; the outer shaft is associated with and rotates a forward group of rotors, while the inner shaft rotates a rearward group of rotors. The switch positions are determined by a detent system of detent-carrying wheels, one for the forward group of rotors and rotatable by the outer shaft, and another for the rearward group and rotatable by the inner shaft. Each wheel is disposed within a respective cavity of a housing of the switch, with the wheel for the forward group disposed in a near end housing and the wheel for the rearward group disposed in a housing member centrally located along the stacked stators. An opposed pair of spring loaded ball detents are carried by each wheel which enter regularly spaced grooves around the inner surface of the cavity-defining wall of the associated end or central housing.
The active surface of the rotor utilized in AMP Part No. 3-436209-4 includes a pattern of arcuate conductive segments constituting the circuit paths which are disposed flush along the dielectric surface to minimize wear of the arcuate shaped free ends of the brush contact portions and the conductive material comprising the circuit paths, for longevity of the switch. Conventionally a circuit board rotor has been made by bonding a metal layer to a dielectric substrate; coating with an etchant resisting material, portions of the metal layer in the pattern of the desired configuration of circuit paths; applying etching solution to the metal layer to remove the uncoated portions of the metal layer, and then rinsing; and finally "backfilling" or filling with dielectric material the grooves left by etching away the metal, to provide a smooth surface to the circuit board.
It is desired to provide a circuit board rotor which is more economical and simpler to manufacture.
It is also desired to provide a rotor and stator combination wherein the brush contacts do not engage corner edges of the metal of the circuit paths especially during substantial in-service use.
It is further desired to provide a rotor which provides for its own positioning.